Watch crystal



July 21, 1925.

A. FRIEDMAN WATCH CRYSTAL Filed Jan. 17, 1925 en I be mama July 21, 1925.

UNITED STATES PATENT OFFICE.

- FBIEDIAN, or'rmsnuaen, PENNSYLYANIA, ASSIGNOR OF ONE-HALF TO mm GLUCK, OI PITTSBURGH, PENNSYLVANIA.

WATCH CRYSTAL.

Application fl1ed January 17, 1825. Serial 10. 8,069.

To all whom it may. concern 'Be it known that I ALEXANDER FRIEDMAN, a citizen of the United States, residing at Pittsburgh, county of Allegheny, State of Pennsylvania, have invente a new and useful Improvement in .Watch Crystals, of which the following -is a full, clear, and exact description.

The present invention relates to watch crystals, and more particularly to watch crystals of celluloid or like material, which are ordinarily known as unbreakable watch crystals. Heretofore, these watch crystals have been made either fiat or slightly convex and have been sprung into the groove of the bezel of the watch. This is ordinarily accomplished by clamping the crystal between male and female dies shaped to increase the convexity of the crystal sufliciently to' allow it to slip*into the groove of the bezel and then releasing the crystal gradually from the clamping pressure of the dies, whereupon the crystal, in tendin to assume 1ts normal shape, makes a tight it in the groove of the bezel. By bending up the crystal and fitting itin the bezel, the crystal is placed under tension and its tendency to unbend and force the edges thereof outwardly is depended upon to hold the crystal in the bezel. Under the heat of the body, a crystal secured and held in place in this manner tends to lose its spring and to warp, thereby increasing its deformation due-to the bending up of the crystal in placing it-in the bezel so that thecrystal becomes loose in the bezel, and if it does not actually drop out, dirt is allowed to sift into the watch casing around the loose edges of the crystal.

In accordance with the method of my present invention I form a watch crystal of the unbreakable type by taking a flat blank of material, such as celluloid, and molding it between heated dies so as to produce a raised or embossed body portion having a ermanent downwardly extending and pre erably outwardly inclined peri heral shoulder terminating in an outwar ly extending bezelaging edge portion off-set into a plane Fow the ralsed or embossed body portion of the crystal by saidpermanent shoulder. This gives the body portion of the crystal a dome shape which, with the permanent shoulder adjacent the ede of the crystal, gives more space beneath t e crystal, so that the ends of the watch hands do not have to be bent over towards the face of the watch, and gives more s ace for the free movement of the hands. he width of the outwardly extendm edge portion will be determined by the size of the particular watch with WlllCll the crystal is to be employed, and will be trimmed accordingly, and since the crystal 1s molded to permanent shape, it does not depend upon being sprung into place to hold it in the bezel. Furthermore, by reason of the permanent shoulder, and also by reason. of t e fact that the body portion of the crystal is molded substantially fiat and under heat, the heat of the body does not .110-

fect the crystal so as to cause it to become loose and drop out of the bezel.

The nature of my invention will be more fully understood by reference to the accompanying drawings, in which Figure l-is a plan View of the bezel of an ordinary round watch having a crystal embodying my invention;

Figure 2 is a section on the line 11-11 of Fi ure; 1, and

igures 3 and 4 are perspective views and Figure 5 a plan view of different shapes of clglystals embodying my invention and adapte for use with wrist watches, theselast three figures showing the crystals complete except for the final step of trimming their edge portions to the desired width to fit the bezels of the watches with which they are to be employed.

Referring to Fi ures 1 and 2, 2 designates the bezel 0 an or inary round watch and 3 the crystal,"wh ich will ordinarily be of celluloid. The crystal is molded so as to have aslightly convex body portion and a downwar ly extendin and outwardly inclined peripheral shoul er 4. This shoulder terminates in an outwardly extending bezel engagin edge portion 5 which is ofi-set b the shoul er 4 into a plane below the omeshaped body of the crystal. This edge portion is trimmed to the proper width so as to enable it to snap into the groove 6 of the bezel.

Figures 3, 4 and 5 illustrate crystals for wrist watches at one stage of their process of manufacture, namely, before the final step of trimming their bezel-engaging edge portions. Since the crystals shown in these three figures merely differ from each other in shape, a description of the process of manufacturing the crystal shown in Figure 3 will suflice. This crystal is made by taking a blank of celluloid or similar material and molding it between heated dies to give it the shape shown. It has the raised or em- 5 bossed substantially fiat body portion 7, the

peripheral shoulder 8 and the flange 9 off-set belowthe raised body. portion by the-shoulder 8. This flange is adapted to be trimmed to the desired width, as, for example, along the dotted line 10, to provide the bezel-engagingedge portion of the proper width to fit the particular size of wrist watch with which the crystal is to be employed.

The process of manufacturing the crystals shown in Figures 4 and 5, as already stated,is the same as the process of making the crystal p. -shown in Figure 3. In Figures 4 and 5 the I 'jarts corresponding to the parts of Figure 3 are designated-\by the same reference numerals with a prime allixed in the case of Figure 4 and a double prime afiixed in the case of Figure 5.

The above examples are'simply illustrative of my invention, it being apparent that 5 the invention is not confined to any par the free movements of the watch hands, substantially as described.

2. A watch crystal of the unbreakable type having a body 'portion which is substantially unafi'ected by ordinary tempera- 'ture changes, and a permanent downwardly inner edge of a bezel without any substantial distortion of said body portion.

3. A watch crystal of the unbreakable type having a heat-treated body portion vwhich is substantially unaffected by ordinary temperature changes, and a permanent downwardly extending peripheral shoulder terminating in an outwardly extending bezel-engaging portion, the free edge of which is adapted for insertion in the groove vin the inner edge of a bezel without any substantial distortion of said body portion.

4. A watch crystal of the unbreakable type havinga body portion, and a permanent downwardly extending and outwardly inclined peripheral shoulder terminating in an outwardly extending bezel-engaging edge portion, the free edge of which is adapted for insertion in the groove in the inner edge of a bezel without any substantial distortion of said body portion, the ofi'setting of said body portion from said edge portion by said shoulder providing additional space between said body portion and the watch dial for the free movements of the watch hands, substantially as described.

In testimony whereof I have hereunto set my hand.

' ALEXANDER FRIEDMAN. 

